"I always feel so welcome in the USA and all of you guys have always been so cool and amazing to play too� So I am really so sad that I'm letting you down like this," she wrote on her Facebook page. "But this is a big opportunity for me, one that people around me won't let me decline. I am seriously so sorry to everyone I have let down, and I really do hope that you will be able to make the rescheduled dates (I'm figuring them out right now) and that you will enjoy the new music that is coming very very very soon."

On her Twitter page, Charli XCX added that the U.S. dates are being moved to cover the months of October and November. "At the end of the day, I've always said, when it comes to pop music for me, if it's good, I like it," the singer told Radio.com during a recent interview while dismissing the concept of musical "guilty pleasures."

"I know that sounds like a really obvious statement, but there is a lot of really terrible pop music, but there's also a lot of amazing pop music," she said. "Some that doesn't even get recognized as pop music, but it is. As long as it's emotional and passionate, I like it."